Orno Test 1

Orno Test 1 - Huntington Beach Trip April 19 Avian...

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Unformatted text preview: Huntington Beach Trip April 19 Avian Evolution As a taxonomic group, birds are the most successful individuals of the terrestrial vertebrates o Recognize over 9,800 species Depend entirely on the metabolic production of heat o Endothermic Highly variable in size, color, behavior, flying ability, and body proportions o Largest living bird Ostrich About 150kg o Smallest living bird Scintillant Hummingbird About 2.25g In terms of their basic structure, they are more uniform in their structure compared to the mammals Birds as Flying Machines o Have the ability to carry out powered flight for long periods of time/distances Weight Reducing Adaptations o Generally have a higher metabolism than other mammals their size o Make them as light weight as possible to facilitate them getting into the air o Skeleton is made up of extremely lightweight and delicate bones Skeleton only makes up about 4.4% of the total body weight of a pigeon Skeleton of a frigate bird only weighs 114 grams although it has a 7ft wingspan Less than the weight of the feathers that cover the body Very elastic structure Necessary for the rigor and stress of flying Combination of lightness and strength comes form the evolution of hollow thin bones and a fusion of bones that are typically separated form each other in other species Sacral vertebrae have been fused together Bones of the hip girdle have been fused together o Molded into a thin tube like structure called the synsacrum o Coracoid bones make up the keel Reduced to a simple coracoid process in human beings Bones of the skull are almost paper thin Tailbone is made up of a series of fused caudal vertebrae o Called the pygostyle In the hand area, the finger bones are reduced in size and number o 2 are missing and 2 of the other 3 are fused together into a single bone Adjacent ribs are strengthened by overlapping braces o Known as uncinate processes o Stabilizes the thoracic basket Sternum has a flattened bladelike structure in flying birds o Referred to as the keel o Where the wing muscles are attached o Well adapted feathers Adapted for fanning the air during flight Primary and secondary feathers are important for lift and thrust Heat conservation Allow the bird to insulate itself against the elements as temperatures have changed over geologic time o Will fluff during cold weather to create air pockets Will fill up with warm air to keep the body warm Think they first evolved to protect the birds from the UV rays from the sun and preserve heat in the avian body Sleek against the body Streamlines the bird and creates less wind resistance Non-living structures o Weight-reducing air sacs Have 2 lungs Smaller and more inelastic than mammalian lungs There are extensions of the lungs called air sacs Serve as reservoirs in the body Some air sacs will penetrate into the larger bones of the birds...
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Orno Test 1 - Huntington Beach Trip April 19 Avian...

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